Many controlled and continuous irrigation devices are well-known, particularly for vases of flowers or plants situated on balconies or terraces. These are utilized especially during holiday periods, or at other times when the homeowner may be away.
Most of the examples in the prior art are electronic devices, essentially having an electronic programmer connected to a running water supply through an open tap and having at its output a series of hoses arranged such as to reach the plants which have to be watered. The programmer sets the watering modalities by programming a timer and the device acts on a valve connected to the tap and regulates the flow of water from the supply to the hoses. The user sets a series of buttons and/or knobs provided on the programmer and has only to select the irrigation program he or she wants, and the program does the rest: watering time, duration of watering operation, day of watering, and so on.
Such devices, however, present some drawbacks, one of which being that the device itself is dependent on an electrical supply, so that the water supply cannot be turned off, which the user usually prefers to do when leaving his or her dwelling for a long time period.
A further drawback is that the tap has to be left open, and if, during the user's absence, the device should become faulty, there might ensue a constant and very damaging flow of water into the room housing the device.
A still further drawback is the high cost of these devices, in relation to their occasional use, which is usually only on the occasions when the user leaves his or her house for a long period of time.
The present applicant addressed the above problems in the device disclosed in patent IT 1,234,704, which has a water container and distributor provided at its base with a plurality of outlet holes for the water and an open bath to receive said water. The bath is housed internally of the container and is pivoted on the container at a horizontal axis corresponding to its center of gravity (calculated when the bath is full). A valve is provided which acts on a supply pipeline of water to the bath to control the water supply to the bath. The device further comprises a counterweight to maintain the bath in a water-receiving position and to bring the bath back into the same position after it has emptied itself into the container by rotating on its axis.
The above solution adequately solves the problem of providing a constant but small quantity of water so as to avoid overflow risks, but has drawbacks deriving from impurities contained in the irrigating water. Where the salt (especially calcium) content of mains water is high, residues form about the tap and cause a diminution, or at least variations, in the water delivery rate.